Welcome to the forum~
I know how you feel as far as all the feelings that you are experiencing. It is an awful feeling and you do indeed wonder how you are going to get through another day. I have no remedy to this as I go day to day wondering if i can do it just one more day. the only thing that gets me by is the one thing I look forward to in my life i would have to do without!!! Im not sure if you have anyone or anything that gives you incentive to go just another day but that is what I have.
Even after 22 years, I still have days that i struggle with, and i mean struggle. I thank god everyday that I do have something in my life that sustains me.
As far as St Johns Wort, that is a natural herb so you might want to check out what it is derived from. SAMe, I have heard good and bad. I tend to stay away from over the counter things because of the severity of my depression. I have a hard enough time managing my depression with meds that are proven to "work" rather than try something that may not work.
Again, welcome and good luck in your search and know that there are many people here that really care about each other.